Ayahuasca is an Amazonian psychoactive plant decoction containing the serotonergic 5-HT2A agonist N,N-dimethyltryptamine (DMT) and monoamine oxidase-inhibiting alkaloids (harmine, harmaline and tetrahydroharmine) that render it orally active. Ayahuasca ingestion is a central feature in several Brazilian syncretic churches that have expanded their activities to urban Brazil, Europe and North America. Members of these groups typically ingest ayahuasca for many years with a frequency of at least two times per month. Prior research has shown that acute ayahuasca increases blood flow in prefrontal and temporal brain regions and that it elicits intense modifications in thought processes, perception and emotion. However, regular ayahuasca use does not seem to induce the pattern of addiction-related problems that characterize drugs of abuse or other neuropsychiatric problems associated with long term drug use.
To study the impact of repeated ayahuasca intake, here we assessed potential drug abuse-related problems, personality, psychopathology, life attitudes and neuropsychological performance in regular ayahuasca users. A group of 127 users and 115 controls were studied at baseline and 1 year later. Controls were actively participating in non-ayahuasca religions.
At baseline assessment, ayahuasca users showed significantly lower scores than controls on the ASI Alcohol Use, and Psychiatric Status subscales. At one year follow-up these differences were still significant in a sub-sample of ayahuasca users. Ayahuasca users showed higher Reward Dependence and Self-Transcendence and lower Harm Avoidance and Self-Directedness than controls, as assessed with the TCI. Users scored significantly lower on all psychopathology measures assessed with the SCL-90-R, showed better performance on the Stroop test, the Wisconsin Card Sorting Test (WCST) and the Letter-Number Sequencing task from the WAIS-III, and better scores on the Frontal Systems Behavior Scale (FrSBe). Analysis of life attitudes showed higher scores on the Spiritual Orientation Inventory (SOI), the Purpose in Life Test (PLT) and the Psychosocial Well-Being test (BIEPS). Despite the lower number of participants available at follow-up, overall differences with controls were maintained one year later. In conclusion, the ritual use of ayahuasca does not appear to be associated with the deleterious effects typically caused by drugs of abuse. Also, we found no evidence of psychological maladjustment, mental health deterioration or cognitive impairment in the ayahuasca-using group.